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Now, US Airways passengers can track their checked bags - in real time - by going to the US Airways website, and typing in bag claim information.

US Airways rolled out the service on all flights March 19. It is information the airline already had for internal purposes.

Delta Air Lines was the first U.S. carrier to launch real-time baggage tracking. Passengers can go to the Delta website or download a free app to pull up information from the bar code on their bag-claim ticket.

"The baggage tracking feature is consistently one of the top used features within our app," said Delta spokesman Paul Skrbec. "The last time I checked, about 6,000 people per day were using it to track their bags."

Here's how the US Airways bag-tracking works:

Go to usairways.com and then to "travel tools" and click on "baggage." A traveler types his or her last name, flight confirmation code, or bag-tag number, and the status of the bag pops up.

When passengers check in and check a bag, the airline scans it - then scans it a second time when the bag goes on the plane and a third time when it comes off.

Since 2008, US Airways has had technology at the aircraft ramp to scan all bags, said Melody Andersen, director of customer strategy.

Passengers with a smartphone or iPad, or who use in-flight WiFi can track a bag from check-in to landing.

But if you are on the plane and suspect your bag did not make it, you must deal with it at your destination. Flight crews will not delay a departure to let someone look for it.

"A lot of customers feel more at ease and empowered with the information because they know where the bag is," Andersen said.

"It provides customers with basic information: Do you go to baggage claim services or the carousel when you land," Skrbec said. "It alleviates the stress and the tension that sometimes happens around, 'Is my bag traveling with me?'"

Passengers transferring from another airline, such as British Airways or Lufthansa, can track their bags only after they have been handed over and scanned by US Airways.

US Airways sees it as one more tool to improve the rate of mishandled bags, said airline spokesman Todd Lehmacher.

Last year, US Airways had 2.14 mishandled bag reports filed per 1,000 passengers, according to the Department of Transportation Air Travel Consumer Report. "That was a 20 percent improvement over 2011, good enough for fifth place out of 15" airlines, wrote CrankyFlier.com author Brett Snyder.

Passengers could one day get e-mail notifications about their bag. "Just like you can sign up for flight alerts and whether a flight is on time and gate changes, we are working on alerting them also about their bag," Andersen said.